Levelling device

ABSTRACT

A levelling device for a strip of material contains a first cassette frame unit having a plurality of first levelling rollers with juxtaposed axes of rotation spaced by a first pitch substantially greater than a first diameter of the rollers, each of the rollers having one extremity coupled and driven individually by a motor torque transmission extender. A second cassette frame unit is interchangeable with the first cassette frame unit and contains a plurality of second levelling rollers with juxtaposed axes of rotation spaced by a second pitch substantially greater than the second diameter of the second rollers. A motor drive drives a plurality of motor torque transmission outputs to each of the extenders. The second cassette frame unit includes a torque distribution module disposed and coupled between one extremity of at least one of the extenders and at least two juxtaposed extremities of the second rollers.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority, under 35 U.S.C. §119, of European application EP 112 90 429.7, filed Sep. 22, 2011; the prior application is herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION Field of The Invention

The invention relates to the field of levelling strips of material such as metal strips or plates. It concerns in particular a levelling device according to the claims that is able to level the widest possible range of strip thicknesses.

In particular, it is known that a levelling device for very thick strips (for example several centimetres thick) requires the use of large-diameter levelling rollers and, conversely, that a levelling device for thin strips (for example less than 5 mm) requires the use of levelling rollers of lesser diameter. The levelling rollers are arranged in an upper and lower cassette unit (also referred to as a “cassette frame unit”) forming a levelling device that can be arranged in a levelling installation provided with a structure dimensioned to receive at least the cassettes. Levelling operations on different strips require frames of different sizes on account of the cassettes and the differently sized rollers thereof. Furthermore, the drive elements of the rollers have different characteristics as a function of the choice of cassettes, rollers or frames depending on the settings required by the thickness and strip type, as well as the necessary speeds and pressures related to the drive rollers or supporting rollers. Thus, in most cases, even if a levelling frame can receive interchangeable cassettes having rollers of different sizes (diameter, length) and axes juxtaposed at adjustable pitches, when swapping one cassette for another cassette, other specific drive elements of the rollers also need to be swapped. These operations are complex and onerous, and require long stoppages of the levelling installations.

To reiterate, the untensioned levelling of strips or plates is accomplished by a succession of alternating bends of decreasing amplitude without the application of external traction upstream or downstream in the levelling machine. These levelling machines include two levelling devices, each having a series of rollers with parallel axes placed respectively above and below the strip, the rollers being offset longitudinally and vertically such that they overlap, forming an undulating path for the strip which is then subjected to successive alternating bending effects. These alternating bends result in curves, generating deformations in the strip that vary from a traction state in the extrados of the curve to a compression state in the intrados, via a zero value in the middle axis or “neutral fiber” of the strip. Depending on the amplitude of the curve, the stresses so generated exceed the elastic limit of the material over a greater or lesser fraction of the thickness thereof. This plastic deformation is essential for eliminating non-developable flatness defects such as “edge wave” and “center buckle”, as well as reabsorbing “developable” flatness defects. The fraction of the thickness of the plastically deformed strip is commonly expressed as a percentage of the total thickness and referred to as the “plastic deformation rate”.

The levelling operation is controlled by controlling the curves generated at each alternating bend, and there are two difficulties related to this control. Firstly, the modelling of the curve as a function of the thickness of the strip, the overlapping of the upper and lower rollers and the gap between the rollers. To make this modelling more precise, successive lower and upper rollers are preferably arranged in a simple pattern, positioning the axes thereof at the apexes of successive triangles. Secondly, the extent of the “deflection” of the levelling machine under the effects of the separation forces between the lower and upper rollers, the deflection being taken into account when applying the tightening stresses of the rollers.

Such levelling machines have been known for a long time and are described in numerous documents, for example international patent disclosure WO 2008/099126 filed by applicant.

In general, each levelling device, respectively lower or upper, includes a plurality of rollers having parallel axes and, normally, a reduced diameter, and are therefore supported by at least two supporting rollers which may themselves be supported on rows of rollers, all of these rollers and rollers being assembled on a chassis.

These two levelling devices, placed respectively below and above a horizontal plane of movement of the strip, are placed in a supporting chassis or frame with four columns arranged on either side of the longitudinal movement axis of the strip and rigidly connected at the bottom thereof by a stationary back plate and at the top thereof by crossbeams, the whole forming a closed frame.

The lower levelling device bears against the stationary back plate and, on the opposite side, the upper levelling device bears against the upper part of the frame. The upper levelling device may be rigidly connected to a beam movable vertically between the four columns using mechanical or hydraulic pistons, such as to control the gap between the two levelling devices and, consequently, the overlapping of the rollers, taking up the separation stresses caused by the resistance of the product.

Commonly, at least some or all of the levelling rollers are driven in rotation about the axes thereof in order to advance the strip or plate by friction, at a given speed, along an undulating path between the lower and upper rollers.

The diversity of standard formats of rolled strip placed on the market is such that a single installation may be required to produce and level strips or plates within a very wide range of different thicknesses, for example from 5 to 50 mm, or more. In a conventional triangle arrangement of three levelling rollers, it can be noted that, for a given pitch and a given overlapping of the rollers, the radius of curvature of a thick strip is much less than the radius of curvature of a thin strip, which results in a much higher plastic deformation rate. Accordingly, for a given plastic deformation rate and with all other things being equal, the overlapping precision required is therefore necessarily greater for a thick strip than for a thin strip.

Published, European patent application EP 1 584 384 proposes using several types of upper and lower levelling devices having a different number of rollers of different diameters and incorporating geared distribution systems to enable switching between one number of rollers to another using a single motor drive. These distribution systems ensure that each roller of the different devices is driven in rotation by a connectable distribution extender shaft, one of the extremities of the extender shaft being detachable from the roll and the other extremity thereof being connected to an additional distribution box, itself directly driven by the motor drive. This arrangement has the major drawback of considerably increasing the volume of the devices to be removed during essential operational roller changes, since the interchangeable cassette frame units containing the rollers also include a large number of transmission extender shafts (in particular for a device containing several small-diameter rollers) and the additional geared distribution box is large (containing an equal number of geared outputs with each of the shafts). Inevitably, if the cassette frame units require more small-diameter rollers, the number of extenders required increases considerably.

BRIEF SUMMARY OF THE INVENTION

The present invention addresses the problems in the prior art by proposing a levelling installation that primarily provides for the levelling of a very wide range of strip thicknesses. By way of example, this range ought to cover thicknesses from several millimetres to several centimetres. For this purpose, knowing that the range of strip thicknesses requires equipment having arrangements of rollers of different diameters, the present invention also proposes ensuring that the coupling of these different rollers with the unique and fixed motor drive devices is interchangeable so as to obviate the need to supplement (and therefore over-dimension) or even swap the fixed motor drive devices. Finally, the present invention is also intended to minimize the number of transmission shafts, known as extenders, and to obviate the need to change the arrangement of the extenders, regardless of the diameters of the rollers and the number of rollers in the different detachable, interchangeable devices that can be used to level strips having significant thickness variations, such as a variation of several centimetres.

For this purpose, the present invention concerns a levelling device for a strip of material. The levelling device contains a first cassette frame unit having a plurality of first levelling rollers with juxtaposed axes of rotation spaced by a first pitch substantially greater than the first diameter of the first rollers, each of the rollers having one extremity coupled and driven individually by a motor torque transmission extender. At least one second cassette frame unit is provided and is interchangeable with the first cassette frame unit and contains, instead of at least one of the first rollers, a plurality of second levelling rollers with juxtaposed axes of rotation spaced by a second pitch substantially greater than the second diameter of the second rollers (either without any of the first rollers remaining or in addition to at least one of the first rollers). A motor drive drives a plurality of motor torque transmission outputs to each of the extenders. The first roller diameter is greater than the second roller diameter. The second cassette frame unit includes at least one torque distribution module arranged and coupled between one extremity of at least one of the extenders and at least two juxtaposed extremities of the second rollers.

Such a levelling device is therefore proposed by the features of the claims.

Advantageously, the torque distribution module is thereby arranged and coupled between the second rollers of the second cassette frame unit and the extenders, the extenders therefore being formally the same as the extenders of the first rollers of the first cassette frame unit. This feature means that, regardless of the number or diameters selected for the rollers of the second cassette frame, the minimum number of extenders required remains the same as for the plurality of first rollers: the number of extenders need not be changed or increased. Furthermore, the extenders need not be swapped and consequently the operations required to swap the cassette frame units are greatly simplified.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in a leveling device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of the specific embodiment when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a diagrammatic, top plan partial view of a levelling device having a first cassette frame unit, extenders and a motor drive thereof according to the invention;

FIG. 2 is a top plan partial view of the levelling device having a second cassette frame unit, the extenders and the motor drive thereof;

FIG. 3 is a top partial view of the levelling device having a second mixed-roller cassette frame unit, the extenders and the motor drive thereof;

FIG. 4 is a top view of individual motor drives of the extenders;

FIG. 5A is front view of the levelling device having a first cassette frame unit, extenders and motor drive;

FIG. 5B is a side view of the levelling device having the first cassette frame unit, the extenders and the motor drive;

FIG. 6A is a front view of the levelling device having a second cassette frame unit, extenders and motor drive; and

FIG. 6B is a side view of the levelling device having the second cassette frame unit, the extenders and the motor drive.

DESCRIPTION OF THE INVENTION

FIG. 1 is a top view of a levelling device according to the invention. The levelling device contains a first cassette frame unit C1 fitted with first levelling rollers R1 individually driven via extenders A1 to a motor drive unit Re1, Ac1, M1, Re2, Ac2, M2.

Similarly, FIG. 2 is a top view of a levelling device according to the invention having a second cassette frame unit C2 fitted with second levelling rollers R2 driven via the same extenders A1 by the same motor drive unit as in FIG. 1.

Also similarly, FIG. 3 is a top view of the levelling device according to the invention having a second cassette frame unit C2 fitted with a combination of first and second levelling rollers R1, R2 driven via the same extenders A1 by the same motor drive unit as in FIG. 1 or 2.

For these FIGS. 1, 2 and 3, the motor drive unit drives a plurality of motor torque transmission outputs for each of the extenders A1 and includes a motor unit M1, M2, a coupling unit Ac1, Ac2 and an output torque reduction gear unit Re1, Re2 linked to the extenders. In the arrangements in FIGS. 1, 2 and 3, each motor, coupling and reduction gear/spindle housing unit is doubled, for example (see FIG. 5A, front view) according to a 4 and 5 torque transmission output schema to ensure torque distribution over 4 or 5 extenders driving the levelling rollers. Nonetheless, any other arrangement of the motor drive unit is possible. Therefore, for example, FIG. 4 shows an individual motor drive arrangement in which each roller R1 is driven by a single motor M1, M2, M3, etc. individually coupled (via individual couplings and reduction gears Ac, Re to each of the extenders A1, which makes it possible to apply relative differences between the different motor torques on each of the extenders, as flexibly as possible. More generally, the motor drive (depending on the different motor/coupler/reduction gear branches) can then include measures for distributing torque to the extenders in dependence on dimensional features, mechanical properties and flatness of the levelled product, as well as the arrangement of the cassette frame unit C1 or C2 connected. It should also be noted that the fact of swapping one cassette frame unit for another cassette frame unit according to FIGS. 1 to 4 does not require the insertion or removal of a new element (intermediate drive, torque output/torque reduction gear, etc.) between the elements in each of the motor/coupler/reduction gear/extender branches. In other words, when swapping cassette frame units, the extenders can remain rigidly connected to the motor drive unit.

FIGS. 5A and 5B show respectively front and side views of the levelling device containing the first cassette frame unit C1, the extenders and the motor drive according to FIG. 1. For the sake of clarity, FIG. 5A only shows the first rollers R1 of the upper and lower cassettes of the cassette frame unit C1 shown in FIG. 5B. In this example, the cassette frame unit C1 includes four upper levelling rollers and five lower levelling rollers laterally offset from the upper rollers. The levelling rollers are mounted rotatably on each upper and lower part of the cassette frame C1 by bearings P1 supporting the extremities thereof. Each of the extremities of the levelling rollers, the first rollers R1 having a first diameter D1, is driven by an extender A1, itself driven by the motor drive unit according to FIG. 1 or 4, the motor drive unit distributing an individual motor torque to each of the extenders driving the upper and lower levelling rollers.

FIGS. 6A, 6B show respectively front and side views of the levelling device containing the second cassette frame unit C2 having been swapped with the cassette frame unit C1 in FIGS. 5A and 5B, the extenders and the motor drive according to FIG. 2 or 4. The second cassette frame unit C2 according to FIG. 6A includes, unlike FIG. 5A, eight levelling rollers in the top of the frame and ten levelling rollers in the bottom of the frame. The levelling rollers, referred to as the second rollers, have a second diameter D2 that is less than the first diameter D1 of the first rollers R1 according to FIG. 5A or 5B. In other words, the first rollers are able to level strips or plates of material that are thicker than the strips or plates levelled by the second rollers.

Similarly to the first rollers R1, the second rollers R2 are mounted rotatably on each upper and lower part of the second cassette frame unit C2 by bearings P2 supporting the extremities thereof. It should be noted that in the example chosen for FIGS. 1, 2, 5A, 5B, 6A and 6B, the levelling widths of the second rollers are identical to the levelling widths of the first rollers and therefore enable strips to be levelled regardless of the width thereof. For this purpose, the driven extremity of each first roller R1 includes a portion long enough to accommodate the bearing P1 thereof, and also long enough to enable the second cassette frame unit C2 to be dimensioned exactly like the first cassette frame unit C1 and to place the bearing P1 thereof while enabling the second bearing P2 and a torque distribution module MDC1, MDC2 to be provided in the portion provided for (initially for the first rollers), but at each driven extremity of the second roller R2.

Therefore, and more generally in the example in FIGS. 1, 2, 5A, 5B, 6A and 6B, the invention provides a levelling device for a strip or plate of material containing:

a first cassette frame unit C1 having a plurality N1 of first levelling rollers R1 with juxtaposed axes of rotation spaced by a first pitch substantially greater than the first diameter D1 of the rollers, each of the rollers having one extremity coupled and driven individually by a motor torque transmission extender,

at least one second cassette frame unit C2 that is interchangeable with the first cassette frame unit C1 and contains a plurality N2 of second levelling rollers R2 with juxtaposed axes of rotation spaced by a second pitch substantially greater than the second diameter D2 of the second rollers,

at least one motor drive M1 driving a plurality N1 of motor torque transmission outputs to each of the N1 extenders,

the first diameter D1 being greater than the second diameter D2, and

the second cassette frame unit C2 incorporates at least one torque distribution module MDC arranged and coupled between one extremity of at least one of the N1 extenders A1 and at least two juxtaposed extremities of the second rollers R2.

The levelling device according to the invention therefore enables the cassette frame units C1, C2 to be detachable from the set of N1 extenders such that they can be swapped without disconnecting the set of N1 extenders rigidly connected to the motor drive. This simplifies swapping and, moreover, it is not necessary to modify the number or type of extenders. It is only necessary to uncouple the extenders from the extremities of the rollers in order to reconnect the extenders to the extremities of the torque distribution module to be driven, following replacement of a new cassette frame unit. Only the repositioning E3 of coupling sleeves between extenders and rollers or torque distribution module is necessary (see FIGS. 5B, 6B), because the pitch and the height of the rollers E1, E2 of the upper and lower roll units differ as a function of the arrangements thereof when they are swapped (see FIGS. 5A, 6A). Furthermore, the levelling device according to the invention enables the end sleeves of the extenders A1 closest to the two cassette frame units C1, C2, assumed to be horizontal for the first cassette frame unit C1 (see FIG. 5B, to be moved and held in position in two dimensions in a vertical and/or horizontal plane to enable coupling either to one extremity of the first roller (see FIG. 5B or to a drive input of a torque distribution module in dependence on the pitch and height between rollers (see FIG. 6B). This feature is clearly visible in FIG. 6B in which it is notable that, although the motor drive unit is unchanged, the extenders A1 have been moved vertically to be attached to the drive input of each of the two lower and upper torque distribution modules MDC1, MDC2. The extremities of the extenders therefore ideally include sleeve connectors joining them to the shaft of the extender and universal joints, more generally of the type that enable angular displacement.

Each torque distribution module MDC, MDC1, MDC2, etc. includes at least two coupling outputs incorporating shaped hollow shafts to enable the transmission of torque coming from an extender towards two adjacent rollers R2, each of the outputs being press-fittable to a portion of the extremity of the second rollers R2 adapted to the same coupling shape (adjacent rollers, see FIG. 6A).

The levelling device according to the invention also provides for at least one of the torque distribution modules MDC to be floatingly assembled in relation to the bearings P2 supporting the rollers R2 and the cassette frame unit C2 as it is provided with an input shaft with a shaped extremity to enable the transmission of torque and coupling/uncoupling by simple insertion into the female sleeve of the drive extender A1 located opposite. In FIGS. 6A and 6B, the floating feature is shown schematically using “spring” symbols F1, F2. Thus, even if shaft-extremity alignment deviations occur during operation or swapping of the cassette frame unit, the floating torque distribution module very advantageously absorbs the alignment deviations without transmitting harmful stresses to the levelling rollers and other components of the installation, i.e. without disturbing the levelling machine containing the levelling device according to the invention.

Advantageously, the second cassette frame unit C2, including at least two of the second rollers R2 associated with a torque distribution module MDC, has the same attachment interfaces and connections as the first cassette frame unit C1 fitted with first rollers R1. These attachments and connections are in particular intended for connection to the extenders, as seen above, but also any other electrical or fluid interface. This feature is further facilitated given that the frameworks of the interchangeable cassette frame units are the same size and, even if the positions of the drive inputs are slightly displaced between the frames, at least one extremity of the extenders can be transversally repositioned accordingly. For this purpose, the levelling device according to the invention also provides for the first and second cassette frame units C1, C2 to have precisely dimensioned bearing arrangements on at least one extremity of the first and second rollers to position the first and second rollers in the cassette frame units of identical external dimensions, as well as, as mentioned above, for at least one torque distribution module such that the bench lengths of the first and second levelling rollers are essentially similar or identical.

The number of outputs from the torque distribution module or modules MDC of the levelling device according to the invention may range from 2 to 4, similarly to the above examples illustrated by the figures. Effectively, depending on the motor drives and the torque thereof delivered for the large first diameters D1 of the first rollers, if the second cassette frame unit C2 requires, for levelling-process reasons, a number of second diameter rollers D2 greater than two and/or having the diameter D2 less than the first diameter D1, the number of outputs from the torque distribution module to the second rollers is also increased as a function of the number of second rollers, so that the number of extenders remains advantageously constant for all of the arrangements of the cassette frame unit and the roller diameters thereof.

Equally, the levelling device according to the invention may also include a second cassette frame unit C2 configured to admit a mixed arrangement of first rollers R1 and second rollers R2 coupled to at least one torque distribution module MDC. An example is given in FIG. 3. Accordingly, such a cassette contains different rollers may also be adapted to a product to be levelled under very precise levelling conditions.

Finally, the levelling device according to the invention provides for the motor drive, i.e. motor, coupler and reduction gear, to include means for the controlled distribution of individual torque to each of the extenders as a function of dimensional features, mechanical properties and flatness of the levelled product, as well as the arrangement of the cassette frame unit C1 or C2 coupled. One ideal embodiment of the motor drive unit therefore provides for each extender to be coupled to a single motor drive, this latter delivering a torque that is instantly controllable as a function of the required levelling conditions. 

1. A device for levelling a strip of material, the device comprising: a plurality of extenders being motor torque transmission extenders outputting a plurality of motor torque transmission outputs; a first cassette frame unit having a plurality of first levelling rollers with juxtaposed axes of rotation spaced by a first pitch substantially greater than a first diameter of said first levelling rollers, each of said first levelling rollers having one extremity coupled and driven individually by one of said motor torque transmission extenders; at least one second cassette frame unit being interchangeable with said first cassette frame unit and having a plurality of second levelling rollers with juxtaposed axes of rotation spaced by a second pitch substantially greater than a second diameter of said second levelling rollers; a motor drive driving the plurality of motor torque transmission outputs for each of said extenders; said first diameter being greater than said second diameter; and said second cassette frame unit having at least one torque distribution module disposed and coupled between one extremity of at least one of said extenders and at least two juxtaposed extremities of said second rollers.
 2. The levelling device according to claim 1, wherein said first and second cassette frame units are detachable from a set of said extenders such that they can be swapped without disconnecting said set of said extenders rigidly connected to said motor drive.
 3. The levelling device according to claim 1, wherein said torque distribution module has at least two coupling outputs incorporating shaped hollow shafts to enable a transmission of torque, each of said coupling outputs being press-fittable to a portion of said extremity of said second rollers adapted to a same shape.
 4. The levelling device according to claim 1, wherein: said at least one second cassette frame unit has bearings; said extenders have female sleeves; and said at least one torque distribution module is one of a plurality of torque distribution modules, at least one of said torque distribution modules is floatingly assembled in relation to said bearings supporting said second levelling rollers of said second cassette frame unit and has an input shaft with a shaped extremity to enable a transmission of torque and coupling/uncoupling by simple insertion into said female sleeve of one of said extenders disposed opposite said input shaft.
 5. The levelling device according to claim 1, wherein in said second cassette frame unit, at least two of said second levelling rollers associated with said torque distribution module, have a same attachment interfaces and connections as said first cassette frame unit fitted on said first levelling rollers.
 6. The levelling device according to claim 1, wherein said first and second cassette frame units have bearing configurations to position said first and second rollers, said bearings also positioning said torque distribution module such that bench lengths of said first and second levelling rollers are one of similar or identical.
 7. The levelling device according to claim 1, wherein said torque distribution module has a number of outputs varying from 2 to
 4. 8. The levelling device according to claim 1, wherein: said torque distribution module has a drive input; and said extenders have end sleeves, said end sleeves closest to said first and second cassette frame units can be moved in two dimensions in a vertical and/or horizontal plane to enable a connection either to an extremity of said first rollers or to said drive input of said torque distribution module in dependence on a pitch between said rollers and the diameters the rollers.
 9. The levelling device according to claim 1, wherein said motor drive includes means for distributing torque to said extenders in dependence on dimensional features, mechanical properties, a flatness of a levelled product, a configuration of said first and second cassette frame units, and a connection of said first and second cassette frame units.
 10. The levelling device according to claim 1, wherein said motor drive is one of a plurality of motor drives and each of said extenders is coupled to a single one of said motor drives.
 11. The levelling device according to claim 1, wherein said second cassette frame unit is configured to admit a mixed configuration of said first rollers and said second rollers coupled to said at least one torque distribution module.
 12. The levelling device according to claim 5, wherein said interfaces and connections attach to said extenders. 